Bugfixes and compatibility with RC4

[sylvainjule]

• https://github.com/TimOetting/kirby-color/commit/897b764caef453e84e0ee0cb2b462b31b2b82a6c

Fixes https://github.com/TimOetting/kirby-color/issues/3

• https://github.com/TimOetting/kirby-color/commit/d66ed352cd187cdb694f4d0e0a8bdb32eefc07b5

Fixes an error thrown when there's no preset (presets is then undefined so checking for presets before checking presets.length is needed)

• https://github.com/TimOetting/kirby-color/commit/df32cbca3be3471ba9f5c981709480f30380fa22

Removes the vue-on-click-outside dependency, which had some flaws:

Instead there's a simpler way of doing it : listening to the blur event to close it as soon as the field loses focus. (edit: with the pitfall of having to check whether the focus has been lost in favor of the color-picker, see https://github.com/TimOetting/kirby-color/pull/5/commits/9ab35a5d53ba3c85b79addbfcecacc0ede530abf)

• https://github.com/TimOetting/kirby-color/commit/d0e9af5e88867ed5ed4af4504d256cd1db432e32

Since the field doesn't rely on the value prop itself, value needs to be watched in order to set the color prop when it changes through actions outside of the field itself (ie when a structure fieldset changes, for example):

Issue before:

Fix:

• https://github.com/TimOetting/kirby-color/commit/f69faab965f90da8406c2cf8ee337a272a6594b3

Anticipating when my previews plugin will not be needed anymore for core fields, remaining previews will only be for plugin fields, I think it's best to have them directly handled by plugins themselves, rather than by an additional one.

[SebastianEberlein]

Thanks a lot for forking and updating the field, @sylvainjule .

Could you also add the help: and translate: false options for the field?